Re: Yard Light goes off several times during the night.

That still sounds like a sensor problem if your light is indeed a
mercury light and not a metal-halide.

The way to diagnose these sorts of problems is to divide and conquer.
To eliminate the photocell, remove it and run the light. If the light
continues to go out then you know the cell is OK. If not, then you've
isolated the problem.

"photocell eliminators" are available from electrical supply houses
that replace the cell and short the red and black wires together for
continuous operation. You can, of course, just stick a jumper into
the socket or open the photocell and wedge the relay contacts closed
with a toothpick or something similar.

I've never seen a mercury bulb fail by flickering. Normally the
failure is via blackening of the arc tube caused by electrode
sputtering. Ultimately the black coating will absorb enough energy
that the arc tube melts and blows out. The light output is so low at
that point that the bulb is replaced before the blow-out.

It could be the ballast IFF the ballast has a thermal overload built
in. Most don't. The ones I've seen with thermal protection have all
had those one-time thermal fuses that blow once and require
replacement.

I'm betting on the photocell. Deposits eventually build up on the
cell, causing leakage current that adds to the cell's conductivity to
cause the relay to trip at a much lower light level that would be
normal. I occasionally moonlight with a local electrical co-op and we
repair a LOT of security lights. Essentially all winking problems are
caused by photocell problems.

If you can stand the color, I recommend replacing the mercury light
with an HPS one, preferably one of the color-corrected ones. A 175
watt sodium light generates the same illumination as a 400 watt
mercury light. If you're paying for the power, that's a significant
saving.

John

On Wed, 01 Mar 2006 06:19:27 -0600, maradcliff@xxxxxxxxxxxx wrote:

I have one of those mercury yard lights on a pole. (Common farm
light). It used to work fine, but recently I find it going off
several times during the night. It goes dark, and then comes back on
in a few minutes. Maybe the bulb is going bad, but in the past they
would just stop working and that was all. I doubt it's the sensor
because that seems to work fine, comes on when it gets dark, goes out
in the morning. Of course anything is possible. I should mention
that the light is not reflecting up into the sensor, or nothing has
changed with the mounting since this started going off and on a couple
months ago. Of course the weather is cold, but it did not do that
other winters, except occasionally during heavy snow storms, but I
always figured that was caused by the snow on the sensor.
Anyhow, I am trying to see if anyone else has had this problem and
what caused it. I know electricity well, and have even worked for
electricians when I lived in the city, but we didn't have these lights
in the city. I know there is not a loose wire or anything, and
checked all of that. It's the light itself. There are only 4 working
parts, bulb, ballast, sensor and socket.
I am sure the socket is fine, so that leaves the bulb or ballast (or a
sensor that has gone whacko).

Anyone????

BTW: This isa 70W bulb.

Thanks
Mark
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
A foolish consistency is the hobgoblin of little minds.-Ralph Waldo Emerson
.

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